Chimpanzees of the Budongo Forest : Ecology, Behaviour, and Conservation

females present. Before 9 a.m., there was an inverse relationship between the copulation
rate and the percentage of time spent feeding. After 9 a.m. the rate of both copulating
and feeding declined, reaching a low point in the heat of the midday period. Both rates
picked up sharply at the start of the afternoon, but while feeding time continued to
increase until nesting, copulation rates declined in the latter part of the day. This is
shown in Fig. 6.4.

Copulation and time of day 121

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

7 8 9 10 11 12 13 14 15 16 17

Hour

Copulation rate

High Ranked Males (DN, MA, BK)

Other Males

Fig. 6.3: Copulation rates per hour for high and low ranking males (M. Emery Thompson, in prep.).

50

60

70

80

90

100

7 8 9 10 11 12 13 14 15 16 17

Time of day (7 = 7:00 –7:59)

Per cent of scans feeding

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Copulations per hour

% scans feeding Copulation rate (per hour

with oestrous females)

Fig. 6.4: Copulation rate and percentage of time spent feeding (M. Emery Thompson, in prep.).